ATV ignition help!

[Flashpoint]

I recently picked up a Yamaha Moto4 ATV from the BST which is a 350cc made between 1991 and 1995. The seller had bought it from an estate sale and knew little about it, except when the starter solenoid was bypassed it cranked and ran. I rode it around his property and it shifted fine, seemed to have good power and ran well although it didn't always hold an idle, but it had been sitting who knows how long before the sale.

So I get it home and notice that the battery + lead is only connected to the starter solenoid and that's it, the rest of the bike is not getting power and the battery is not getting charged. The two "control" wires (3+4) of the solenoid were ripped off of it and it was impossible to tell what color they had been. Mega kudos to anyone who chooses to delve into this, lol!

I've replaced the solenoid with a new amazon one (currently it's just dangling) and the colors from it don't match the diagram in the manual, and the colors from the manual don't match exactly the wires dangling from the bike either. As you can see there is supposed to be a blue/white (L/W) and a black ground wire as control inputs to the solenoid but the connecter coming from the bike is blue/white and red/white (3+4). What's worse is that the red/white wire of the 3/4 pair from the bike should be black to ground in the manual but I ohmed it out and it's not ground. Also the random red wire (5) tapped off of the main red from the battery was looped back to the battery when I got it, lol. I suspect that it should be connected to the un-numbered red and white wire dangling above the 3+4 connector in the pic. I didn't find any trace of the fuse holder shown in the diagram.

My big question is, should it be relatively safe to just connect things the way I think might be correct or in your opinion would I risk blowing out a transistor, etc. somewhere. I'm hoping someone here either has experience with something similar or could just offer general advice. Any suggestions are appreciated!

 

[JoeR]

If you wire it incorrectly there is a very real risk of breaking something expensive. If you trust your wiring skills, and trust your wiring diagram, then by all mean go ahead and fix it. If not, I bet you could find a whole wiring harness on ebay or at a scrap yard for ATVs. That would be safer than winging it.
Joe

 

[Flashpoint]

If you wire it incorrectly there is a very real risk of breaking something expensive. If you trust your wiring skills, and trust your wiring diagram, then by all mean go ahead and fix it. If not, I bet you could find a whole wiring harness on ebay or at a scrap yard for ATVs. That would be safer than winging it.
Joe

The wiring diagram does not match the vehicle, but is the same/similar to other diagrams I have found online. Not sure what is up with that. If I took the thing apart enough to replace the wiring harness I could probably trace the wires and figure it out myself. Trying not to have to tear the whole thing apart.

 

[Marturo]

Retired Mechanic now, Yamaha 1972 to 1980s.

If this came in as a basket case to our shop, I would just put it back to stock first.
That includes all fuses & safety's & test what I could before power up.

You want smoke & fire? Trying to patch a Jap bikes electrical system will only lead to disaster.
Sorry but after a lifetime of wrenching if I learned anything it was don't F around with the electrical
systems on foreign vehicles. Do it their way.

So I get it home and notice that the battery + lead is only connected to the starter solenoid and that's it, the rest of the bike is not getting power and the battery is not getting charged.

Lord knows why anyone would wire it like this???

 

[Flashpoint]

So yesterday I looked at this again and realized the only problem was that I was afraid to attach the solenoid control connector to the connector coming from the bike because the wire that was supposed to be ground was not. All that connection does though is supply +12v and ground to the solenoid control leads when the start button is pressed, and the stock start button feels like it is broken (doesn't depress noticeably) so I just installed my own momentary contact start button to do that.

Turns out that the random red wire that was looped back to the battery was plugged in to the connector where the dangling red/white wire was supposed to go, so I removed that wire and plugged the connector back together the way it should have been.

Now it cranks/starts/runs and I have working headlights. Dash lights still out though and I'm not sure if the battery is charging, but so far so good!

BTW anyone know the spark plug and oil drain plug socket sizes? The $40+ manual I bought sucks in that regard. The one spark plug socket I own is too small and the drain plug is just being a bitch. Really needs an oil change. The filter I ordered came and it is comically small, lol.

I hooked it up briefly to my little bush hog of which pullng is its main duty just to see how well it would pull it and with that low range it does an awesome job. Still needs an oil change before it gets put to work and hopefully that idle will smooth out.

 

[Flashpoint]

Got some fresh oil in her this morning and put her to work.


Someday I'll learn how to hold a phone when taking video with my left hand, sorry.

That is what I have been pulling with a Home Depot John Deere riding mower but the mower deck would occasionally catch the little stumps and it was like hitting a brick wall. I'm really surprised that mower took all that abuse and keeps on ticking. No issues like that with the ground clearance of an ATV!

Next I'm going to try and get the dashboard lights working. The ignition (key) switch, the kill switch, and the headlight switch work but I'd really like that Oil Temp light to work since I'm going to be pulling stuff real slow in hot weather. It is oil cooled thankfully.